Cho Seung Hui paused Monday morning during the shootings at Virginia Tech to stop at a post office and mail to NBC News in New York a disturbing package of pictures, writings and video before returning to the rampage.

The communications sought to explain his actions but served mostly to display his anger and illness. With threatening images and in a menacing video, America's deadliest gunman photographed himself wearing black and a backward baseball cap and pointing handguns at the camera and himself. He blamed rich people and humanity at large for the perceived wrongs that drove him to kill.

A $14.40 U.S. Postal Service express parcel, which had the wrong Zip code and an incorrect street address, was sent from Blacksburg at 9:01 a.m. Monday, about two hours after Cho's first two killings at a dormitory, West Ambler Johnston Hall.

About 45 minutes after mailing the package, he went to Norris Hall and killed an additional 30 people before killing himself as police closed in. As if trying to justify his plot, Cho glared into the camera and in a rambling diatribe said: "You had a hundred billion chances and ways to have avoided today," according to excerpts aired last night by NBC. "But you decided to spill my blood. You forced me into a corner and gave me only one option. The decision was yours. Now you have blood on your hands that will never wash off." "Jesus loved crucifying me," he said at another point. "He loved inducing cancer in my head, terrorizing my heart and ripping my soul all this time."

"I didn't have to do this," he said. "I could have left. I could have fled. But no."

Investigators have been mystified by the gap -- from 7:15 to 9:45 a.m. -- between the bursts of homicide Monday, and the university has been criticized for a perceived lack of urgency during the lull.

The Virginia State Police superintendent, Col. Steve Flaherty, said Cho's package "may be a very new critical component of this investigation. We are in the process . . . of attempting to analyze and evaluate its worth."

Cho, who has been described by classmates and teachers as brooding, withdrawn and silent, also left a rambling, angry, multi-page document in his dorm room. He wrote at least one bomb threat that police found, as well as a novel and some disturbing poems and plays.

Law enforcement sources said his letter to NBC was nearly identical to the ones found in his dorm room. All mention his disgust toward the privileged and contain the cryptic words "Ismael Ax," which also was tattooed on one of his arms. Authorities are trying to figure out what the words mean.

The authorities had investigated Cho for bothering two female classmates in 2005, Tech Police Chief Wendell Flinchum said at a news conference. Cho had hinted at suicide shortly afterward and was temporarily committed, against his will, to a psychiatric hospital for evaluation.

There he was assessed as "mentally ill" but not an imminent danger to himself or others, according to court documents. Because he was not a threat, he was released, the documents say. Campus police said they had no more encounters with Cho.